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Curves of potentiometric titration of fully protonized fibrous ion exchangers with potassium hydroxide against the background of 1 M KCl in the presence of chlorides of Ni2+, Со2+, Сu2+ and Ca2+ were obtained. The ion exchangers were synthesized by modifying of industrial polyacrylonitrile fiber with diethylenetriamine and triethylenetetraamine and predominantly contained functional groups R-CO-NH- (CH2CH2NH)nH (n = 2 or 3) and a small amount of carboxyl groups. The sorption of Ni2+, Со2+, Сu2+ и Ca2+by ion exchangers was calculated from the data obtained depending on the pH of the medium. It was found that the investigated ion exchangers with high selectivity sorb heavy metal ions in a wide range of acidity of solutions (pH 2–9) due to the formation of metal-polymer complexes with polyamine functional groups. The maximum sorption capacity is 1.5–2.7 and 4–5 meq/g for ion exchangers with n = 2 and 3, respectively.

Titration curves of H-forms of the fibrous chelating sorbent with iminodiacetic groups based on industrial polyacrylonitrile fiber Nitron with potassium hydroxide in 1M KCl solution in the presence of Ni2+, Co2+, Cu2+ and Ca2+ chlorides were obtained. The method used made it possible to simultaneously measure the pH of the solution and the concentration of the divalent cation at each point of the titration curve. From these data, the dependences of their sorption values on the pH of the equilibrium solution were calculated. The curves of direct and back titration practically coincided in all cases. As the pH changed during titration, precipitation was observed at pH values of precipitation of the corresponding hydroxides. In this case, the increase in pH was suspended or greatly slowed down by adding alkali to the titration cell. The formation of a precipitate occurred mainly in a solution for Co2+ and Ni2+ (pH 8), when the ion exchanger was saturated with a metal ion. In the case of Cu2+ (precipitate formation pH 4), Cu2+ sorption occurs at both lower and higher pH due to ionization of carboxyl groups and partial dissolution of the precipitate. In all cases, the maximum sorption of Ni2+, Co2+, Cu2+, Ca2+ corresponded to the formation of sorption complexes of the R–N(CH2COO-)2Me2+ type.

By the method of potentiometric titration of a fibrous aminocarboxylic polyampholyte with a predominant content of carboxyl groups, the equilibrium of the cation exchange of calcium, magnesium, and potassium ions for a hydrogen ion was studied. Due to the low solubility of calcium and magnesium hydroxides in these cases, titration was carried out by Ca(OH)2 and Mg(OH)2, which are formed in solution upon contact with the H-form of the ion exchanger оf increasing portions of solid CaO and MgO. This made it possible to obtain titration curves in a wide range of pH and calcium and magnesium chlorides concentration (0–0.1 eq./L). The dependences of the swelling of ion exchangers on the neutralization degree with the bases of the studied cations are obtained. The coefficients of ion-exchange equilibria are calculated. It was found that the swelling of the ion exchanger is relatively little dependent on its ionic form. The ion exchanger has a higher affinity for calcium than magnesium ion.

Structural and electronic characteristics of molecular models of swollen polyacrylic and sulfostyrene-type cation exchangers in sodium and potassium ionic forms are calculated within the non-empirical HF/basis set method using the MINI Huzinaga basis set and the Firefly program. The obtained data are compared with those for water clusters of a comparable size. The molecular models include four and two monomeric units of corresponding polymers with ten water molecules per functional group; the water clusters contain 20 and 40 water molecules. The following characteristics of the model structure are obtained: the number and the types of the nearest neighbors of cations and water molecules; the distances between the interacting ions and the atoms; the orders of interionic and ion-molecular bonds; binding energy distribution of water molecules in the systems; number and length distributions of hydrogen bonds; the number and character of $$\text{RCO}_{2}^{-}\cdots {{\text{I}}^{+}},\ \text{RSO}_{3}^{-}\cdots {{\text{I}}^{+}}\ \text{and}\ {{\text{H}}_{\text{2}}}\text{O}\cdots {{\text{I}}^{+}}$$ bonds. The lengths of hydrogen bonds and the total number of intermolecular and ion-molecular bonds per water molecule in water clusters are established to be similar to those in Na+ and K+ molecular models of ion exchangers. The first coordination layer around both ions is filled with oxygen atoms of water molecules and fixed anions. The coordination numbers of Na+ and K+ are almost equal to those in aqueous solutions. The calculations indicate that direct interaction of Na+ and K+ with the anionic groups is responsible for the difference between their ion exchange selectivities on carboxylic and sulfostyrene ion exchangers. The Na+ ion forms direct largely covalent chemical bonds with the fixed carboxylate anion. The K+ ion forms long electrostatic bonds with the carboxylate group. This accounts for a higher selectivity of Na+ on carboxylic ion exchangers than that of K+. The K+ ion forms long direct electrostatic bonds with the fixed sulfonate anion. The Na+ ion does not form direct bonds with the sulfonate due to strong hydration of the former. This accounts for a higher selectivity of K+ on sulfonic acid resins that that of Na+.

A mathematical model for description of the sorption capacity of ion exchangers on alkaline compounds protonizable in aqueous solutions (exemplified by ammonia, mono-, diand triethylamine) was proposed. The Henry’s constants for these substances were experimentally determined. The model accounts for the concentration and acid-base properties of the sorbate, relative air humidity, acid-base properties and exchange capacity of the ion exchanger, as well as spatial availability of functional groups for interaction under conditions of limited permeability of polymeric ion exchanger. The applicability of the model is illustrated by processing the experimental results on the sorption of ammonia and ethylamines by fibrous carboxylic and sulfonic cation exchangers. Good agreement between the calculated and experimental data is observed.

The perspectives of using ion-exchange soils for growing plants in zero-gravity field are described. Standard methods for obtaining ion-exchange soils are not suitable for weakly dissociating ion-exchangers. Methods for obtaining ion-exchange soil based on weakly dissociating fibrous ion exchangers are proposed. The method using concentrated solutions made it possible to obtain ion-exchange soils with a larger content of deficient ions (K+ , NO3 – ). The suitability of the obtained ion-exchange soils was confirmed by a biological experiment.

BACKDROUND This study presents the evaluation of two ion exchangers (granular and fibrous) impregnated with nanoparticles of hydrated ferric oxide (HFO) as selective sorbents for phosphate recovery from aqueous solutions. The hybrid impregnated anion exchangers combine the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of HFO towards phosphate species. Dynamic experiments were carried out and data obtained were fitted to a well-known fixed-bed sorption model. RESULTS The theoretical sorption capacities reported by the Thomas model were in good agreement to the breakthrough experimental capacities determined from the sorption data. The sorption capacity decreased when using wastewater treatment plant secondary effluents in comparison with synthetic water mainly due to the presence of organic matter and suspended solids. The phosphate sorbed on the impregnated ion exchangers were efficiently desorbed by using a 0.5 mol/L sodium hydroxide solution, reporting up to 90% of recovery. CONCLUSION The reusability of sorbents was evaluated through five sorption–desorption working cycles. Fiban-As was able to operate up to three consecutive cycles with good sorption performance whilst a significant decrease of sorption capacity after the first cycle was observed for FO36 resin.

This study presents the evaluation of a fibrous ion exchanger impregnated with nanoparticles of hydrated ferric oxide (HFO) as a selective sorbent for phosphate. The hybrid impregnated anion exchanger (FIBAN-As) combines the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of HFO towards phosphate species. The phosphate loading capacity at the common pH of waste waters treatment plant secondary effluents was 162 ± 12 mg PO43-/g sorbent. Dynamic experiments were carried out and data obtained was fitted to fixed-bed sorption models. The theoretical sorption capacities reported by the Thomas model were in good agreement to the breakthrough experimental capacities determined from the sorption data. The sorption capacity decreased in multicomponent system due to the faster ion exchange of competing anions compared to phosphate ions. The loaded FIBAN-As was efficiently regenerated by using a sodium hydroxide solution, reporting up to 90% of recovery. Finally, reuse of FIBAN-As was evaluated in three successively sorption–desorption cycles by using two regeneration solutions. A sorption capacity reduction of 23% and 30% was observed for acid and alkaline solutions, respectively after the third cycle

Quantum-chemical calculations of vibrational spectra of the sulfonated ion-exchanger model p-ethylbenzenesulfonic acid hydrated by 1–10 water molecules and its dimer were calculated by the non-empirical SCF MO LCAO method with the 6-31G(d) basis set. The calculated results were compared with experimental IR and Raman spectra of sulfonated ion exchangers. The infl uence of hydration on the vibrational frequencies of functional groups in the ion exchangers was analyzed. It was shown that the sulfonic acid was completely dissociated if three and more water molecules per functional group were present. Bands near 1130 cm–1 were due to S–O–H bending vibrations in the absence of water molecules and C–S–O–H3O combination vibrations with 3–6 water molecules per sulfonic acid.

A model for potentiometric analysis of spatial polyampholytes has been developed. It allows calculation of acidity parameters for all kinds of functional groups in the sorbent and reconstruction of the full titration curve of polyampholyte from the state of complete protonation (strong acid medium) to the state of complete deprotonation. Synthesis of new amino-carboxylic polyampholytes by reacting a PAN fiber with hydrazine and sodium sulphide is described. Computer analysis of potentiometric titration curves shows that the new polyampholytes contain four types of functional groups.

Weak base polyfunctional fibrous anion exchangers, containing small amount of carboxylic acid groups were obtained on the base of industrial modacrylic fibers Kanecaron (40% acrylonitrile, 60% vinylchloride) (Kaneka Ltd., Japan) by their reacting with aqueous solutions of diethylenetriamine (DETA). The sample obtained at optimal condition (DETA concentration 70–80%, process time 2–7 h, temperature 95 °С) have anion exchange capacity 3–5 meq/g and water uptake 0.3–0.4 gH2O/g. Their chemical stability in different media has been studied. On the base of studies of their ion exchange capacity, elemental analysis, potentiometric titration and IR spectra the structure of these ion exchangers has been clarified. Predominant reaction of the modification is substitution of the Cl atoms by nitrogen in DETA molecules with formation of tertiary and secondary amino groups. All three atoms of nitrogen react and the ratio of incoming N atoms and outgoing Cl atoms is close to one.

We have developed a method for producing an atomically smooth (surface roughness within 0.2 nm over an area of 1000 nm2) gold surface and depositing Au nanoparticles (3–13 nm) on it via a self-assembly process.

Acid–base properties, kinetics and equilibrium sorption of Ca 2+ , Cu 2+ , Pb 2+ , Cd 2+ , Ni 2+ and Mn 2+ ions on fibrous chelating ion exchanger FIBAN X-1 containing iminodiacetic group have been studied. The structural and electronic characteristics of ion-polymeric complexes have been obtained by non-empirical quantum chemical calculations. The rate of sorption processes was extremely high; the half-process time of the sorption process was equal to 24 s. The isotherms of ion sorption are described by the Langmuir equation what allowed deriving equation for dependence of the distribution coefficient on the ion concentration and accurate extrapolation of these value to zeros concentration. The concentration range the Henry’s law applicability was determined theoretically and proved experimentally. The sorption selectivity series in a neutral medium was Cu > Ni > Pb > Cd > Mn > Ca. The same series follows the pH at which the sorption begins. Complete extraction of all heavy metal ions occurs at pH > 4. The quantum chemical calculations have shown that the selectivity of sorption is determined by the number of coordination bonds between the cation and fixed anion, the length of the bonds and degree of their covalence. The way of combining of these factors is individual for each specific cation and can be revealed by quantum chemical calculations.

The use of Fe(III)-EDTA complexes as catalytically active components was shown to be a promising technique in the construction of contact gas purifiers for the removal of hydrogen sulfide from gas-air mixtures. Nonwoven fabrics obtained on the basis of Fiban ion-exchange fibers and an Fe(III)-EDTA complex have good barrier properties with respect to the hydrogen sulfide of the air. The possibility of strengthening the fabrics by combining them with reinforcing materials has been demonstrated.

Hydrogen chloride sorption from the air in a wide range of relative humidity and the concentration of the absorbing component was examined under dynamic conditions with fibrous anion exchanger FIBAN distinguishing by basicity and type of functional groups.

Sorption system based on a hydride material produced by impregnation of a fibrous polyacrylonitrile anion-exchanger with potassium permanganate was studied. Tests on purification of potable water to remove tri- and pentavalent arsenic compounds were performed and demonstrated a degree of purification to below the maximum permissible concentrations established by regulations of the World Health Organization.

Ion exchange equilibria Cl−– NO 3 - , Cl−– SO 4 2 - , NO 3 - – SO 4 2 - on fibrous strong base anion exchangers on the basis of graft copolymer of styrene and divinylbenzene to polypropylene fibers with groups of benzyl trimethyl- (TMA), triethyl- (TEA), and tributyl- (TBA) ammonium have been studied and characterized by values of the equilibrium coefficients and separation factors. They were compared with the same equilibria on ion exchange resins Dowex1 with different cross-linkage. An equation allowing calculating the separation factor for different ionic concentrations and ratios of the ions in solutions of uni- and divalent ions from the equilibrium coefficient invariant to the concentration has been derived. The selectivity of nitrate and chloride sorption increases with increasing size of alkyl radicals in the functional group and with increasing percent of divinylbenzene in the resins. A quantity characterizing selectivity of ion exchanger to bivalent ion against the univalent ion named concentration of zeroth selectivity (CZS) has been suggested to describe the efficiency of ion exchangers in processes of water purification from univalent ions, specifically nitrates in waters containing sulfates. At concentrations above the CZS the univalent ion is absorbed selectively compared to the bivalent one; the “dumping effect” in frontal chromatograms of mixtures of such ions is not possible above the CZS point and this criterion can be used for choosing the ion exchanger for selective removal of univalent ions from mixtures with polyvalent ones. The CZS values for conventional strong base ion exchangers in ion exchange NO 3 - – SO 4 2 - is higher than typical total ionic concentrations in drinking waters (1–3 × 10−3 eq/L). For Dowex1 × 10 it was found equal 1.3 × 10−2 eq/L. For the fibrous ion exchanger with benzyltributylammonium groups CZS = 3.3 × 10−6 eq/L. This ion exchanger is suitable for selective removal of nitrates from the solutions with concentrations higher than this value and has exceedingly high selectivity to nitrates which makes the process of its regeneration difficult. The most suitable fibrous ion exchangers for application in drinking waters purification from nitrates with guarantied absence of the nitrate dumping appeared FIBAN A-1 TEA having the CZS values 4.3 × 10−4 eq/L.

The interaction between nitrogen dioxide and aqueous carbamide on a fibrous ion exchanger in a gas-purifying filtration apparatus at 20 ± 5°C is considered. An empirical equation describing dynamic nitrogen dioxide absorption by the reactive filter material is suggested. The process is applicable to the treatment of ventilation emissions containing nitrogen dioxide.

It has been established that fibrous polymeric ion exchangers can be impregnated with nanoparticles of hydrated ferric oxide (HFO) which serves as a selective sorbent for As(III) and As(V) species from aqueous solutions. The screening studies have shown that the largest amount of Fe(III) can be loaded into a weak base anion exchanger with ternary amino groups (up to 1.4 mmol Fe/gram of dry fiber). The fibrous composite sorbent on the base of such anion exchanger possess a high selectivity toward both As(III) and As(V) species combined with a high sorption capacity (∼2.9 g As/kg till As concentration in outlet solution becomes more than 10 μg/L). The sorbent does not release Fe into contacting solution and does not require backwashing in column operations. Its specific feature is extremely high rate of the sorption processes. The process rate is controlled by diffusion of the arsenic species into HFO particles uniformly spread in the fiber. The half process time appeared equal 23 s which allows column operation with empty bed contact time down to 10 s. The sorption of As(III) at pH values admissible for drinking water is not affected by the foreign anions ( Cl − , SO 4 2 − , H 2 PO 4 − / HPO 4 2 − ) . Sorption of As(V) decreases with phosphates concentration increasing. Column experiments with model and natural waters containing As in concentrations 50–100 ppb have shown that the new sorbent can be used for production of small water household filters with the filtering bed volume about 0.5 L. The filter allow purification of 200 L of water per hour and obtaining 2.5–5 tons (5000–10 000 bed volumes) of purified from As(III) and As(V) water without correcting pH and pre-oxidation of As(III). The field experiment on purification of natural water containing 60 ppb of As allowed purification of 10 000 bed volumes of water to 10 ppb of As in the effluent.

The interphase distribution of hydrogen halides (HF, HCl, HBr, and HI) and oxygen-containing acids (H2SO4 and HClO4) in a system with the binary extracting agent methyltrioctylammonium dinonylnaphthalenesulfonate was studied. It was found in the extraction of mineral acids depending on the aqueous acidity, that the distribution ratios of mineral anions B m− decreased with pH in accordance of the laws of binary extraction. The extraction isotherms of mineral acids were obtained, and the apparent constants of extraction were calculated.

We investigated the processes of zinc regeneration of carboxylic ion exchangers FIBAN by the solutions of sulfuric acid and sodium sulfate. It is shown that the mode of direct-flow continuous elution of the ion exchanger by the regeneration solution is not promising enough. It is planned to carry out regeneration by the solution of sulfuric acid circulating through a sorbent layer. For preparation of the ion exchanger for a new cycle of sorption it is recommended to treat the material with a mixed solution of sodium hydroxide and sodium sulfate.

The anion exchange fibers on the basis of industrially produced polyacrylonitrile fiber NITRON with different strong and weak base groups have been described in the paper. Their acid–base properties were characterized by the acidity parameters calculated from the potentiometric titration curves. The method of computer analysis of the titration curves described elsewhere was used. It was established that the ion exchange fibers are polyfunctional and contain at least four types of functional groups. Their capacities and the acidity parameters have been calculated. The fibers have full ion exchange capacity about 3.5 meq/g. The capacity according to the strong base quaternary aminogroups (p K ≅ 2) is usually about 2.5 meq/g. The water uptake, stability in hydrogen peroxide solutions, strong acids and alkalis of different concentrations at the ambient temperature and 100 °C have been studied. The fibers do not loose significantly their anion exchange capacities and mechanical properties except for the most extreme regimes of their treatment. At the same time they accumulate carboxylic acid groups in their structure due to hydrolysis of the residual nitrile groups in the fiber.

Sorption of sulfuric acid and lithium sulfate by the sulfate form of ion exchanger Dowex 1×8 have been studied in the range of concentrations 0.025–2 M. The regularities observed were described with the help of mathematical and computer models similar to those used for description of sorption of HCl and HClO4 in the previous communication [Soldatov et al. React. Funct. Polym. 60 (2004) 41]. The models account for the site sharing effect, Donnan distribution and dimerisation of hydrosulfate ion in the resinous phase. The main introduction in the sorption of sulfuric acid in the studied concentration range is done by conversion of sulfate to hydrosulfate counterion. Dimerisation of hydrosulfate and Donnan distribution becomes important at a concentration of the external H2SO4 solution above 1 M. Sorption of lithium sulfate is entirely controlled by the Donnan distribution.

Sorption of hydrochloric and perchloric acids and their sodium salts was studied by Cl− and ClO4− forms of ion exchanger Dowex 1×8 in the concentration range of the external electrolyte 0.25–4 mol/l. Sorption of water and the total amount of the solution were also studied. Sorption of the acid appeared markedly higher than that of the respective salts. A mathematical modeling and computer simulation of the processes were performed. The overall sorption was represented as a superposition of the Donnan membrane distribution and formation associates type RAn · (AnKt)i · (H2O)n in the homogeneous resin phase. The model expresses non-ideality of the resin phase in explicit form as formation of the above associates characterized by the constants of their formation. A good agreement between the experimental and calculated sorption in the whole concentration range was obtained in the assumption of two associates with i=1, 2 and n=1–3. The same factors control sorption of the acids and the salts and the difference in their behavior has a quantitative character. The main introduction into the overall sorption of the salts makes the Donnan distribution up to concentration of the external electrolyte 4 M, while the main part of the absorbed acids is contained in the associates.

Treatment of drinking water to remove heavy metal ions Pb2+, Cu2+, Cd2+, Co2+, Ni2+, and Zn2+ with commercial fibrous carboxylic ion exchangers FIBAN Kh-1, K-3, K-4, and K-5 was studied. Features of metal ion sorption from two-component solutions were determined. A comparative evaluation of the sorption selectivity of FIBAN fibrous ion exchangers with respect to heavy metal ions was made.

A method for determination of the acidity parameters of ion exchangers with arbitrary functionality from potentiometric titration data was developed. Titration of ion exchanger RH (ROH) with alkali KtOH or acid HAn is considered as superposition of ion exchange H + –Kt + (OH − –An − ) and the reaction of neutralization. The method is based on the assumption of linear dependence of logarithm of the equilibrium coefficient of the ion exchange as a function of the neutralization degree. The acidity parameters are two constants of this dependence. They are thermodynamic equilibrium constant of ion exchange, p K and the difference between logarithm of the equilibrium coefficient at the complete and zeroth neutralization of the ion exchanger, Δp k . Specially developed computer program allows reconstruction of the potentiometric titration curve from the sets of the acidity parameters of each type of the functional groups in the resin. The theory was tested on a number of ion exchangers with different functionalities: sulfonic and carboxylic acid cation exchangers, polyfunctional weak base anion exchangers of different structures. The ion exchange capacity of each type of groups can be determined with precision higher than 0.1 meq/g. The p K i values of the groups present in macroamounts are determined with precision at least ±0.2 p K units.

The effect of minor additions of ion exchange substrates Biona and mechanical mixtures of ion exchangers, saturated with a full set of biogenic elements, on the productivity of sand and garden soil was investigated. The addition of 2% of substrate Biona increased the crops by four to five times for soil and four to eight times for sand. The effect of the addition of the mixture of the monoionic forms was also very pronounced (two to three times) while less than that of the addition of the ion exchange substrate. Results of the experiments showed that ion exchanger substrates could be used for fertilization of depleted soils.

The effect of the nature of exchangeable cation (Na+, Mg2+, Ba2+, La3+) in FIBAN K-1 fibrous sulfonic cation-exchange resin on sorption of tetramminepalladium(II) and its cross-sectional distribution in fabrication of Pd catalysts is studied.

Fibrous ion exchangers (FIBAN) have been studied in a model process of water softening and removal from water simultaneously present heavy metal ions: Co2+, Ni2+, Zn2+, Cd2+, Cu2+, Pb2+. The effect of the following factors on the efficiency of Ca2+ removal from a model solution has been studied: the filtering bed height (7–40 mm); density of the column packing corresponding to the volume capacity, 0.17–0.83 meq/cm3; solution flow rate (4–37cm/min). A fibrous sulfonic-type ion exchanger in shallow beds has exhibited a high efficiency in removal Ca2+ from water, greatly exceeding efficiency of a conventional sulfostyrene resin studied in parallel. In all cases high breakthrough capacities corresponding to the degree of column utilization, 0.6–0.9, have been observed. In the processes of water purification from heavy metal ions the highest efficiency was observed for chelating fibrous ion exchanger with iminodiacetete groups. A granular resin of the same type had much lower efficiency. Fibrous ion exchangers can find a wide application in water treatment processes.

Equilibria of ion exchange of neutral aliphatic amino acid cations (A + =Gly + , Ala + , Val + , Leu + ) and H + have been studied on a liquid sulfonic type ion exchanger — dinonylnaphthalene sulphonic acid dissolved in heptane. It has been established that the difference in selectivity of extraction of these cations is much greater than on sulphostyrene resins, which is a favourable precondition for their selective extraction. The selectivity coefficients of the H + –A + exchange have a region of a low dependence on the degree of loading of liquid ion exchanger ( X =0 –0.5) and a region of a sharp decrease ( X >0.5) . This phenomenon is explained as a result of formation of very stable complexes of the amino acid cations and the anion of dinonylnaphthalene sulphonic acid containing one unsubstituted proton per 3–6 A + cations. The IR spectra confirm this assumption. The dependence of the selectivity coefficient on the degree of H + –A + exchange has been described using the previously developed mathematical model of ion-exchange processes. The model is consistent with the experimental data in an assumption that four nearest neighbours of an exchange centre in the associates of the liquid ion exchanger influence the energy of ion exchange on a given exchange site.

The effect of compression of a stearic acid Langmuir monolayer on the interaction of copper ions with the monolayer and on the formation of interface clusters has been studied as functions of pH and ionic content of the water subphase. Copper binding was estimated by direct electron paramagnetic resonance measurements of ion concentrations in the water subphase. A scanning tunnelling microscopy study of monolayer Langmuir-Blodgett films, deposited on graphite substrates, gave evidence for the formation of nanosized clusters on the monolayer surface. The data obtained showed that the interaction of the monolayer with copper ions and the accompaning cluster formation processes were determined by the arrangement, order and mobility of the stearic acid molecules in the monolayer and the electrostatics at the interface.

The effect of the complexonate solution pH on the nature and amount of ethylenediamine tetraacetate complexes of iron, immobilized on a FIBAN A-5 fibrous anionite, and their catalytic activity in H2S oxidation by molecular oxygen was studied.

Sorption of HCl, HF, SO2 and H2S from their mixtures with air have been studied in dynamic conditions on two types of novel fibrous ion exchangers: a strong base one of type 1 on polypropylene-styrene matrix and a weak base exchanger with amido-amino groups. Influence of the air flow rate, sorbate concentration and air flow humidity have been studied. Conditions for the ion exchangers regeneration with water or soda solutions are described. It has been found that side effects such as sorbate molecules association, water sorption and oxidation of the substances sorbed strongly influence their sorption — desorption behaviour. Characteristics of industrial air filtering plants with fibrous ion exchangers are presented.

A simple model assuming three kinds of micelles has been applied to the K + H + exchange on dimonylnaphtalene sulfonic acid (HDNNS) in the solvents: chloroform, carbon tetrachloride, nitrobenzene and isooctanol, to the Ca 2+ H + exchange in heptane, nitrobenzene and isooctanol. In heptane the following exchanges were also studied: Ag + H + , Cu 2+ H + , Ni 2+ , Fe 3+ H + and Al 3+ H + . Also the water uptake was studied for Ca 2+ H + and K + H + in nitrobenzene as solvent. The three parameters, found to fit each system are collected in Table 2. At present no simple rationalization of these constants seems possible.

Donnees sur l'echange des ions ethylammonium primaires secondaires tertiaires et quaternaires en presence de l'acide dinonylnaphtalene-sulfonique (echangeur de cations liquide) dans de l'heptane, du nitrobenzene et de l'ethyl-2 hexanol. Donnees, aussi, sur l'echange en presence de l'echangeur de cations solide, le KRS-8

Water sorption, heat effects and IR spectra have been studied as a function of water activity for dinonylnaphthalene sulfonic acid (HDNNS) dissolved in heptane. The water sorption data have been interpreted in terms of a set of simple equilibria HDNNS + n H , 2 O ⇌ HDNNS ( H 2 O ) n with the equilibrium constants and species given in Table 1. The heat data have been fitted with the same species and the ΔH°-values given in Table 2 together with the entropy values obtained from a combination of heat and free energy data. The large negative entropy values indicate strong ordering effects in the HDNNS-micelles. The infrared data also indicate that in the HDNNS-aggregates the water is more structurized than in resinous cation exchangers of the polystyrene sulfonic acid kind. They also give some information about the first steps of the hydration process beginning with a break up of the HDNNS-aggregates followed by the formation of hydronium sulfonate. Upon the addition of further water molecules this highly symmetric structure is destroyed.

Ion exchange, water uptake and VPO studies have been performed on the two liquid cation exchangers, dinonylnaphthalene and didodecylnaphthalene sulfonic acids and some of their salts. It is found that didodecylnaphthalene sulfonic acid is slightly less aggregated than dinonylnaphthalene sulfonic acid, its water uptake is also less, but the selectivity is about the same. In heptane the presence of water increases the aggregate size, in benzene this increase is smaller and in chloroform no increase is observed. It is also demonstrated that in the concentration range used, the size of a certain aggregate is practically constant. It has been possible to follow the change in aggregate size during the ion exchange process for the system Al3+ - H+. The fact that the three parameter model applies suggests that the interactions at an exchange site are practically independent of aggregate size.

Ion exchange and water sorption data for the systems (K,H)D and (Ca,H)D (D = dinonylnaphthalene sulfonic acid) in heptane-isooctanol mixtures can be described by a simple equilibrium model for formation of mixed micelles. This model gives the following relation between the experimental quantity Y and the corresponding quantities yi relating to the two pure micelles and the mixed micelle Y=y 1 X 2 +y 2 (1- X ) 2 +2y 3 (1- X ) X = equivalent fraction of metal ion in the organic phase. This equation can be identified with the relation Y=y 1 X +y 2 (1- X )+y′ 3 X (1- X ) used to fit experimental data Y( X ) . The quantity y3 is computed from y 3 = (y 1 +y 2 +y′ 3 2 Both extraction and IR data show that isooctanol forms complexes with the sulfonate partly blocking the ion exchange process.

The potassium-hydrogen exchange on dinonylnaphthalene sulfonic acid dissolved in heptane has been studied in the temperature range 1–80°C using batch techniques and titrimetric analysis. The data can be fitted with a simple model, where it is assumed that the system contains three kinds of micelles, HDNNS-micelles. KDNNS-micelles and a mixed micelle (K. H)DNNS each with a different ion exchange constant. The relation between the experimental value for the equilibrium quotient (κ) and the three parameters κ 1 , κ 2 and κ 3 is log κ= X log κ 1 +{l− X } log κ 2 + X (l− X ) log κ 3 where X is the mole fraction of potassium in the organic phase, i.e. the distribution of micelles is assumed to be statistical. From the curves log κ( 1 T ) x the function ΔH( X ) is obtained at each temperature. These data can be fitted with the same model i.e. δH ° =δH 1 ° X +δH 2 ° (1− X )+δH 3 ° X (1− X ) Together with the free energy data ( ΔG ° = − RT ln κ ) entropies are computed for the three kinds of micelles. It is found that while the two pure micelles have negative entropy changes, the mixed micelle has a positive entropy change, provided the assumptions inherent for the equation above are correct. The mixed micelle concept also explains the water extraction in the system HDNNS-KDNNS in heptane as shown for data at 25°C.

In previous papers in this series it was found[1,2] that ion exchange and water sorption data for dinonylnaphtalene sulfonic acid (HD) in various solvents could be fitted by the expression Y=y1X+y2(1-X)+y′2X(1-X) Y is the property studied and yi the same property related to three kinds of micelles, those corresponding to the pure salts (y1 and y2) and mixed micelles containing both ions (y′3). X is the equivalent fraction of metal ion in the organic phase the H+Me2+ exchange being studied. In the present paper it is shown that if it assumed that the distribution of ions over the three kinds of micelles is random the quantities in eqn (1) can be given a simple physical interpretation.

This article examines a family of ion-exchange fibers, FIBAN, containing primary and secondary amine groups. These ion exchangers have a fiber diameter of 20–40 Μm, high osmotic and mechanic stability, a high rate of adsorption and regeneration, and excellent dynamic characteristics as filtering media. Inparticular, this article discusses the use of FIBAN fibrous ion exchangers in the recovery of gold cyanide andbase-metal cyanides (copper and mercury) from mineral-leaching solutions. The influence of polymer structure and water content on their extraction ability is described, along with key parameters of gold hydrometallurgy such as extraction efficiency, selectivity, pH dependence, gold cyanide loading, kinetics, and stripping.

It was shown directly by chemical experiments that zinc sulfide crystals grown at high temperatures usually contain zinc in amounts above that required by the stoichiometric composition, and very pure specimens may contain no less than 1017 atoms/cm3.